So in our world Queen Isabella of Castile gave birth to twins in 1482. One was Maria of Aragon and the second a stillborn. But what if instead of Maria being the twin, Catherine was and that stillborn was in fact a healthy boy named Ferdinand? How would things go on? Might Henry VII of England favor a double match with Arthur marrying Catherine and Margaret Tudor marrying Ferdinand? Let's assume Arthur dies as otl and Henry VIII marries Catherine, but they have the same luck with children as they did in otl. Would Ferdinand just let Henry treat his twin so badly and divorce her and split with the church or might there be an analogue to the Spanish armada?